Austin Sigg judge OKs use of brain expert for the defense

GOLDEN — The judge in the case against Austin Sigg ruled on Wednesday that defense attorneys may include testimony from an expert on adolescent brain development.

District Court Chief Judge Stephen Munsinger granted the motion on the grounds that the expert speak generally about adolescent brain development — including the effects of trauma — but does not opine directly about Sigg's mental state. Prosecutors in the case expressed concerns that Sigg's attorneys are setting up a "mental state defense."

Sigg is accused of kidnapping, killing and dismembering 10-year-old Jessica Ridgeway in October.

Public defender Ryan Loewer arrives at court for a motions hearing in the Austin Sigg case at the Jefferson County Courthouse, July 10, 2013. (THE DENVER POST | RJ Sangosti)

Munsinger granted the motion over requests from Chief Deputy District Attorney Hal Sargent, who asked that the ruling be postponed until after defense attorneys provided prosecutors with a list of the evidence the expert's testimony would relate to.

Sigg is charged with 18 counts — four carry mandatory life sentences — in Jessica's death and an attack on a jogger at Ketner Lake last Memorial Day weekend. He pleaded not guilty to all charges in April.

Under Colorado law, a defense team is not allowed to introduce expert opinions about the defendant's mental condition if the defendant has not undergone a court- ordered mental health evaluation. By restricting the expert's testimony to general discussions on brain development and not an evaluation of Sigg, defense attorneys avoid triggering the provisions of an insanity defense.

Munsinger cautioned that Sigg's attorneys will have to show the relevancy of the expert's testimony and what evidence it relates to.

He set a Sept. 20 start date for Sigg's trial, which is expected to last three weeks.

Jessica was kidnapped on her way to school Oct. 5, 2012. Part of her body was found five days later in a field in Arvada. Sigg was arrested Oct. 23 after authorities say he confessed on the phone.

District Attorney Pete Weir, right, with members of his legal team arrive at court for a motions hearing in the Austin Sigg case at the Jefferson County Courthouse in Golden on July 10, 2013. (THE DENVER POST | RJ Sangosti)